Syntheses, structures, and properties of two new hybrid Dawson-based polyoxotungstates [Mn(2,2′-bipy)3]H2 [Mn(2,2′-bipy)2][P2W18O62] and [Co(H2biim)3)]2H2[P2W18O62] · 8H2O

Abstract

Two new hybrid Dawson-based polyoxotungstates, [Mn(2,2′-bipy)3]H2[Mn(2,2′-bipy)2][P2W18O62] (1) and [Co(H2biim)3)]2H2[P2W18O62] · 8H2O (2) (2,2′-bipy = 2,2′-bipyridine, H2biim = 2,2′-biimdazole), have been prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, thermogravimetric analyses (TGA), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectra. Compound 1 is a 1-D zigzag chain constructed from alternate Dawson-type heteropolyanions [α-P2W18O62]6− and metal coordination cations [Mn(2,2′-bipy)2]2+, in which the 1-D chains are extended into a 3-D framework through C–H ··· π and π–π stacking interactions. Compound 2 is a discrete structure consisting of [α-P2W18O62]6− and two [Co(H2biim)3)]2+ cations, forming a 3-D supramolecular framework via N–H ··· O hydrogen bonds and C–H ··· π interactions. Photoluminescence properties of 1 and 2 have been investigated at room temperature.